Dingy soils such as body soils and other hydrophobic soils, including dairy soils, are extremely difficult to remove from fabric during a laundering process. The appearance of lipase enzymes suitable for detergent applications in the 1980's (e.g. Lipolase and Lipolase Ultra, ex Novo Nordisk—now Novozymes) gave the formulator a new approach to improve grease removal. Lipase enzymes catalyse the hydrolysis of triglycerides which form a major component of many commonly encountered fatty soils such as sebum, animal fats (e.g. lard, ghee, butter) and vegetable oils (e.g. olive oil, sunflower oil, peanut oil). However, these enzymes show limited performance in the first wash cycle (being effective mainly during the drying stage of the laundering process) and give rise to a post-wash malodor. Without wishing to be bound by theory, the malodor arises from fatty acids released by the hydrolysis of fats and is particularly noticeable for dairy soils like milk, cream, butter and yogurt; dairy fats contain triglycerides functionalized with short chain (e.g. C4) fatty acyl units which release malodorous volatile fatty acids after lipolysis. For a general review of the use of lipases in solid laundry detergents see the following reference: Enzymes in Detergency, ed. J. H. van Ee et al, Vol 69 Marcel Dekker Surfactant Series, Marcel Dekker, New York, 1997, pp 93-132 (ISBN 0-8247-9995-X).
More recently so-called ‘first wash’ lipases have been commercialised such as Lipoprime™ and Lipex™ (ex. Novozymes) which show performance benefits in the initial wash cycle. The Lipex™ enzyme is described in more detail in WO 00/60063 and U.S. Pat. No. 6,939,702 B1 (Novozymes). Laundry detergent formulations comprising the Lipex™ enzyme are described in more detail in IP.com publication IP 6443D (Novozymes). However in order to better exploit lipase technology, both the odour profile on residual dairy stains and the cleaning performance on complex soils still needs to be improved.
Detergent manufacturers have also attempted to incorporate bleach catalysts, especially oxaziridium or oxaziridinium-forming bleach catalysts, in their detergent products in an attempt to provide a good bleaching performance. EP 0 728 181, EP 0 728 182, EP 0 728 183, EP 0 775 192, U.S. Pat. No. 4,678,792, U.S. Pat. No. 5,045,223, U.S. Pat. No. 5,047,163, U.S. Pat. No. 5,360,568, U.S. Pat. No. 5,360,569, U.S. Pat. No. 5,370,826, U.S. Pat. No. 5,442,066, U.S. Pat. No. 5,478,357, U.S. Pat. No. 5,482,515, U.S. Pat. No. 5,550,256, U.S. Pat. No. 5,653,910, U.S. Pat. No. 5,710,116, U.S. Pat. No. 5,760,222, U.S. Pat. No. 5,785,886, U.S. Pat. No. 5,952,282, U.S. Pat. No. 6,042,744, WO95/13351, WO95/13353, WO97/10323, WO98/16614, WO00/42151, WO00/42156, WO01/16110, WO01/16263, WO01/16273, WO01/16274, WO01/16275, WO01/16276, WO01/16277 relate to detergent compositions comprising an oxaziriduium and/or an oxaziridinium-forming bleach catalyst.
There is a continuing need for laundry detergent compositions that exhibit a good overall cleaning profile, a good cold water temperature bleaching performance, good greasy soil cleaning performance and a reduced malodor profile on residual fatty soils, especially dairy soils.
The inventors have found that by using lipase in combination with a bleach catalyst that is capable of accepting an oxygen atom from a peroxyacid and transferring the oxygen atom to an oxidizeable substrate improves the cleaning performance of the detergent composition whilst maintaining a reduced malodor profile on residual fatty soils, especially dairy soils.
In another embodiment of the present invention, the inventors have found that the rubber sump hose compatibility profile is improved when a diacyl and/or a tetraacyl peroxide species is in combination with a lipase.
In an especially preferred embodiment of the present invention, the Inventors have found that using a lipase in combination with (i) a bleach catalyst that is capable of accepting an oxygen atom from a peroxyacid and transferring the oxygen atom to an oxidizeable substrate and (ii) a diacyl and/or tetraacyl peroxide species, significantly improves the cleaning performance of the composition, reduces the malodor profile of the composition and improves the rubber sump hose compatibility profile of the composition.